This invention relates generally to machinist's tools and more particularly concerns tools for checking the accuracy of machining on a workpiece.
The known method for testing the accuracy of a machined workpiece is to hold a flat surface test tool against the piece to be tested with one hand. A light source is then held on one side of the tool with the other hand and the machinist observes from the other side of the tool whether light appears between the tool and the workpiece. This approach is not very efficient for many reasons.
First of all, without even considering the test procedure itself, it is necessary to have both the tool and the light source close at hand. In reality, they are never where you expect them to be when you need them. They are used for other reasons and not returned to the test area or at least not to the place the machinist would look for them. Some machinists keep a light source with them, but pockets and belts can become quickly cluttered and cumbersome.
Secondly, the light sources themselves are not very efficient. They are, typically, point sources such as a flashlight or the like. A proper test should desirably indicate not only the existence of a flaw on the workpiece surface but the location and severity of the flaw as well. Point sources do not disperse light evenly across the surface to be tested. Therefore, they may not always provide accurate information about the flaw.
Finally, the use of an independent light source with the test tool is at best inefficient and cumbersome and, in some applications, nearly if not entirely impossible. The machinist must deal with at least three objects, the workpiece, the test tool and the light source, with only two hands. The machinist's eyes must be on one side of the test tool while one hand holds the tool and the other hand holds and properly directs the light source on the opposite side of the tool. This frequently must be accomplished in situations of limited access so that hand positions are dictated or even prohibited by the workpiece. Often, other objects such as surface plates must be simultaneously manipulated.
It is, therefore, an object of this invention to provide a machinist's accuracy testing tool which has a light source built into the tool. Another object of this invention is to provide a machinist's accuracy testing tool which disperses light from multiple points along the surface of the workpiece. A further object of this invention is to provide a machinist's accuracy testing tool which directs the light from a light source to the appropriate workpiece surface. Yet another object of this invention is to provide a machinist's accuracy testing tool which eliminates the need for holding a light source. It is also an object of this invention to provide a machinist's accuracy testing tool which makes testing more easy, efficient and accurate. Still another object of this invention is to provide a machinist's accuracy testing tool which enables testing to be performed in areas of limited space which might otherwise render testing impossible.